* Improve rank inference for Expand op
Signed-off-by: NTom Wildenhain <tomwi@microsoft.com>

* Unnecessary dtype check in Expand shape inference
Signed-off-by: NTom Wildenhain <tomwi@microsoft.com>

* Add test for Expand rank inference
Signed-off-by: NTom Wildenhain <tomwi@microsoft.com>